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Evidence for sexual recombination in Didymella tanaceti populations, and their evolution over spring production in Australian pyrethrum fields


Pearce, TL and Scott, JB and Pilkington, S and Pethybridge, SJ and Hay, FS, Evidence for sexual recombination in Didymella tanaceti populations, and their evolution over spring production in Australian pyrethrum fields, Phytopathology, 109, (1) pp. 155-168. ISSN 0031-949X (2019) [Refereed Article]

Copyright Statement

Copyright 2019 The American Phytopathological Society

DOI: doi:10.1094/PHYTO-08-17-0280-R


Tan spot, caused by Didymella tanaceti, is one of the most important foliar diseases affecting pyrethrum in Tasmania, Australia. Population dynamics, including mating-type ratios and genetic diversity of D. tanaceti, was characterized within four geographically separated fields in both late winter and spring 2012. A set of 10 microsatellite markers was developed and used to genotype 774 D. tanaceti isolates. Isolates were genotypically diverse, with 123 multilocus genotypes (MLG) identified across the four fields. Fifty-eight MLG contained single isolates and Psex analysis estimated that, within many of the recurrent MLG, there were multiple clonal lineages derived from recombination. Isolates of both mating types were at a 1:1 ratio following clone correction in each field at each sampling period, which was suggestive of sexual recombination. No evidence of genetic divergence of isolates of each mating type was identified, indicating admixture within the population. Linkage equilibrium in two of the four field populations sampled in late winter could not be discounted following clone correction. Evaluation of temporal changes in gene and genotypic diversity identified that they were both similar for the two sampling periods despite an increased D. tanaceti isolation frequency in spring. Genetic differentiation was similar in populations sampled between the two sampling periods within fields or between fields. These results indicated that sexual reproduction may have contributed to tan spot epidemics within Australian pyrethrum fields and has contributed to a genetically diverse D. tanaceti population.

Item Details

Item Type:Refereed Article
Keywords:pyrethrum, population genetics, Didymella tanaceti, tan spot
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Crop and pasture protection (incl. pests, diseases and weeds)
Objective Division:Plant Production and Plant Primary Products
Objective Group:Industrial crops
Objective Field:Plant extract crops
UTAS Author:Pearce, TL (Dr Tamieka Pearce)
UTAS Author:Scott, JB (Dr Jason Scott)
UTAS Author:Pilkington, S (Mrs Stacey Pilkington)
UTAS Author:Pethybridge, SJ (Dr Sarah Pethybridge)
UTAS Author:Hay, FS (Dr Frank Hay)
ID Code:130555
Year Published:2019
Web of Science® Times Cited:3
Deposited By:TIA - Research Institute
Deposited On:2019-02-01
Last Modified:2020-04-01

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